Estimating power headroom report in a secondary cell

Abstract

A method and network node for estimating power headroom report in a secondary cell are disclosed. According to one aspect, a method in a network node includes monitoring a power headroom for a primary cell and for a secondary cell. The method includes configuring the UE to cease transmission of power headroom reports, PHRs, for the secondary cell when a difference between the power headroom of the primary cell and the power headroom of the secondary cell is less than a first threshold. The method also includes estimating power headroom for the secondary cell based at least in part on power headroom of the primary cell.

Description

[0001]ESTIMATING POWER HEADROOM REPORT IN A SECONDARY CELL TECHNICAL FIELD The present disclosure relates to wireless communications, and in particular, to estimating power headroom reports in a secondary cell. BACKGROUND The Third Generation Partnership Project (3GPP) has developed and is developing standards for Fourth Generation (4G) (also referred to as Long Term Evolution (LTE)) and Fifth Generation (5G) (also referred to as New Radio (NR) or Next Generation (NG)) wireless communication systems. Such systems provide, among other features, broadband communication between network nodes, such as base stations, and user equipment (UE), as well as communication between network nodes and between UEs. The 3GPP is also developing standards for Sixth Generation (6G) wireless communication networks. A Power Headroom Report (PHR) is an important component in 5G communication, particularly in the context of power control and resource allocation. It is used by the User Equipment (UE) to inform the base station (eNodeB / gNodeB) about the power headroom it has, allowing the network to efficiently allocate resources and maintain the quality of service. Power Headroom (PH): The power headroom represents the difference between the maximum power the UE may transmit and the actual power it is currently using. It is essentially a measure of the remaining power resources available in the UE for uplink transmissions. Power Headroom Report (PHR): The UE periodically sends a PHR to the network (eNodeB / gNodeB) as part of the uplink control signaling. This report contains information about the UE's current power headroom, expressed as a PH value. The PHR enables the network to make informed decisions regarding resource allocation and power control. Resource Allocation: The network uses the received PHR from the UE to decide how to allocate uplink resources efficiently. If the UE has a high power headroom, it may be assigned more resources, enabling it to transmit with higher power or using more advanced modulation schemes for better data rates. If the PHR indicates limited headroom, resource allocation may be adjusted to ensure that power resources are used optimally. Power Control: PHRs also assist in power control mechanisms. If the network observes that the UE has a significant power headroom, it might reduce the power allocated to the UE to avoid unnecessary interference with neighboring UEs or to save power. If the PHR indicates a low power headroom, the network may allocate more power to ensure reliable communication. In summary, the Power Headroom Report in 5G plays a crucial role in optimizing the allocation of uplink resources and managing power usage efficiently. A high-band sector may have a large bandwidth, which is divided into contiguous cells. These cells are served by a single radio unit. In carrier aggregation, both primary and secondary cells have a continuous frequency range. However, power headroom report is sent to primary and secondary cells independently. The power headroom represents the difference between the maximum power the UE may transmit and the actual power it is currently using. The UE transmit power depends on how many physical resource blocks (PRBs) have been allocated to the UE for uplink (UL) transmission. Thus, it may be said that Power headroom is a function of number of allocated PRBs for UL transmission. Since both primary and secondary cells have contiguous frequency and are served by same radio unit, the PHR for primary and secondary cells should be similar based on PRB allocation, cell bandwidth (BW) and UL signal to interference plus noise ratio (SINR). Thus, receiving independent PHR on primary and secondary cells in carrier aggregation (CA) is an inefficient utilization of uplink resources. SUMMARY Some embodiments advantageously provide methods, systems, and apparatuses for estimating power headroom report in a secondary cell. The channel characteristics of primary and secondary cells in high band are likely to be similar due to their contiguous frequency band. Initially, each cell receives individual PHR. The scheduler monitors: 1. The delta PHR over time; 2. Delta PRB allocation between primary and secondary cells; 3. the cell bandwidth; and 4. UL SINR. to determine the similarity between the PHR of the two cells. If the PHR of primary and secondary cells are similar, the scheduler may estimate the PHR on its own for the secondary cell using the reported PHR on the primary cell and the above-mentioned parameters, instead of relying on PHR from the UE in the secondary cell. Once the scheduler is able to estimate PHR for secondary cell, it may send radio resource control (RRC) reconfiguration to UE to stop sending PHR for secondary cell(s). When both primary and secondary cells have a contiguous frequency band and are served by the same radio unit in high band, their channel characteristics are similar. Consequently, the Power headroom (PH) obtained at the primary cell may be used to infer the PH at the secondary cell. As a result, it is possible to reduce the overhead of requesting the PHR at both the primary and secondary cells, leading to more efficient use of the UL resources. By eliminating the PHR for secondary cells, UL resources may be used efficiently. According to one aspect, a method in a network node configured to communicate with a user equipment, UE, is provided. The method includes monitoring a power headroom for a primary cell and for a secondary cell. The method also includes configuring the UE to cease transmission of power headroom reports, PHRs, for the secondary cell when a difference between the power headroom of the primary cell and the power headroom of the secondary cell is less than a first threshold. The method further includes estimating power headroom for the secondary cell based at least in part on power headroom of the primary cell. According to this aspect, in some embodiments, the method includes monitoring an uplink signal to interference plus noise ratio, SINR. In some embodiments, the process includes configuring the UE to cease transmission of PHRs for the secondary cell based at least in part on the SINR. In some embodiments, the process includes monitoring a primary cell bandwidth and a secondary cell bandwidth. In some embodiments, the process includes configuring the UE to cease transmission of PHRs for the secondary cell based at least in part on the primary and secondary cell bandwidths. In some embodiments, the method includes monitoring a physical resource block, PRB, utilization of the primary cell and of the secondary cell. In some embodiments, the method includes configuring the UE to cease transmission of PHRs for the secondary cell based at least in part on the monitored PRB utilizations. In some embodiments, the method includes configuring the UE to resume transmission of PHRs for the secondary cell upon occurrence of an event. In some embodiments, the event is expiry of a timer. In some embodiments, the event is a change in power headroom of the primary cell exceeding a second threshold. In some embodiments, the event is a difference between power headroom of the primary cell and an estimated power headroom of the secondary cell exceeds a third threshold. In some embodiments, the event is a change in physical resource block utilization exceeding a fourth threshold. In some embodiments, the UE is configured to cease or resume PHR transmissions for the secondary cell by radio resource control, RRC, signaling. In some embodiments, the method includes, when a difference between the estimated power headroom of the secondary cell and a periodically reported secondary cell power headroom reported by the UE exceeds a threshold, configuring the UE to commence transmission of secondary cell PHRs. According to another aspect, a network node configured to communicate with a user equipment, UE, is provided. The network node is configured to monitor a power headroom for a primary cell and for a secondary cell. The network node is also configured to configure the UE to cease transmission of power headroom reports, PHRs, for the secondary cell when a difference between the power headroom of the primary cell and the power headroom of the secondary cell is less than a first threshold. The network node is further configured to estimate power headroom for the secondary cell based at least in part on power headroom of the primary cell. According to this aspect, in some embodiments, the network node is configured to: monitor an uplink signal to interference plus noise ratio, SINR; and configure the UE to cease transmission of PHRs for the secondary cell based at least in part on the SINR. In some embodiments, the network node is configured to: monitor a primary cell bandwidth and a secondary cell bandwidth; and configure the UE to cease transmission of PHRs for the secondary cell based at least in part on the primary and secondary cell bandwidths. In some embodiments, the network node is configured to: monitor a physical resource block, PRB, utilization of the primary cell and of the secondary cell; and configure the UE to cease transmission of PHRs for the secondary cell based at least in part on the monitored PRB utilizations. In some embodiments, the network node is configured to configure the UE to resume transmission of PHRs for the secondary cell upon occurrence of an event. In some embodiments, the event is expiry of a timer. In some embodiments, the event is a change in power headroom of the primary cell exceeding a second threshold. In some embodiments, the event is a difference between power headroom of the primary cell and an estimated power headroom of the secondary cell exceeds a third threshold. In some embodiments, the event is a change in physical resource block utilization exceeding a fourth threshold. In some embodiments, the UE is configured to cease or resume PHR transmissions for the secondary cell by radio resource control, RRC, signaling. In some embodiments, when a difference between the estimated power headroom of the secondary cell and a periodically reported secondary cell power headroom reported by the UE exceeds a threshold, the network node is configured to configure the UE to commence transmission of secondary cell PHRs. BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: FIG.1 is a schematic diagram of an example network architecture illustrating a communication system according to principles disclosed herein; FIG.2 is a block diagram of a network node in communication with a user equipment over a wireless connection according to some embodiments of the present disclosure; FIG.3 is a flowchart of an example process in a network node for estimating power headroom report in a secondary cell; FIG.4 is a known configuration for power headroom reporting; FIG.5 is a configuration for power headroom reporting according to principles disclosed herein; and FIG.6 is a flowchart of another example process in a network node for estimating power headroom report in a secondary cell. DETAILED DESCRIPTION Before describing in detail example embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to estimating power headroom report in a secondary cell. Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and / or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. In embodiments described herein, the joining term, “in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate and modifications and variations are possible of achieving the electrical and data communication. In some embodiments described herein, the term “coupled,” “connected,” and the like, may be used herein to indicate a connection, although not necessarily directly, and may include wired and / or wireless connections. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and / or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The term “network node” used herein may be any kind of network node comprised in a radio network which may further comprise any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multi- standard radio (MSR) radio node such as MSR BS, multi-cell / multicast coordination entity (MCE), relay node, donor node controlling relay, radio access point (AP), transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH), a core network node (e.g., mobile management entity (MME), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc. The network node may also comprise test equipment. The term “radio node” used herein may be used to also denote a user equipment (UE) such as a wireless device (WD) or a radio network node. In some embodiments, the non-limiting terms wireless device (WD) or a user equipment (UE) are used interchangeably. The UE herein may be any type of wireless device capable of communicating with a network node or another UE over radio signals, such as a wireless device (WD). The UE may also be a radio communication device, target device, device to device (D2D) UE, machine type UE or UE capable of machine to machine communication (M2M), low-cost and / or low-complexity UE, a sensor equipped with UE, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (IoT) device, or a Narrowband IoT (NB-IOT) device etc. Also, in some embodiments the generic term “radio network node” is used. It may be any kind of a radio network node which may comprise any of base station, radio base station, base transceiver station, base station controller, network controller, RNC, evolved Node B (eNB), Node B, gNB, Multi-cell / multicast Coordination Entity (MCE), relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH). Note that although terminology from one particular wireless system, such as, for example, 3GPP LTE and / or New Radio (NR), may be used in this disclosure, this should not be seen as limiting the scope of the disclosure to only the aforementioned system. Other wireless systems, including without limitation Wide Band Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM), may also benefit from exploiting the ideas covered within this disclosure. Note further, that functions described herein as being performed by a user equipment or a network node may be distributed over a plurality of user equipments and / or network nodes. In other words, it is contemplated that the functions of the network node and user equipment described herein are not limited to performance by a single physical device and, in fact, may be distributed among several physical devices. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Some embodiments are directed to estimating power headroom report in a secondary cell. Referring to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in FIG.1 a schematic diagram of a communication system 10, according to an embodiment, such as a 3GPP-type cellular network that may support standards such as LTE and / or NR (5G), which comprises an access network 12, such as a radio access network, and a core network 14. The access network 12 comprises a plurality of network nodes 16a, 16b, 16c (referred to collectively as network nodes 16), such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (referred to collectively as coverage areas 18). Each network node 16a, 16b, 16c is connectable to the core network 14 over a wired or wireless connection 20. A first user equipment (UE) 22a located in coverage area 18a is configured to wirelessly connect to, or be paged by, the corresponding network node 16a. A second UE 22b in coverage area 18b is wirelessly connectable to the corresponding network node 16b. While a plurality of UEs 22a, 22b (collectively referred to as user equipments 22) are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding network node 16. Note that although only two UEs 22 and three network nodes 16 are shown for convenience, the communication system may include many more UEs 22 and network nodes 16. Also, it is contemplated that a UE 22 may be in simultaneous communication and / or configured to separately communicate with more than one network node 16 and more than one type of network node 16. For example, a UE 22 may have dual connectivity with a network node 16 that supports LTE and the same or a different network node 16 that supports NR. As an example, UE 22 may be in communication with an eNB for LTE / evolved universal terrestrial radio access network (E-UTRAN) and a gNB for NR / NG-RAN. A network node 16 (eNB or gNB) is configured to include a scheduler 32 which is configured to include a PHR unit 34. The PHR unit 34 may be configured to configure the UE to cease transmission of power headroom reports, PHRs, for the secondary cell when a difference between the power headroom of the primary cell and the power headroom of the secondary cell is less than a first threshold. The PHR unit 34 may also be configured to estimate power headroom for the secondary cell based at least in part on power headroom of the primary cell. Example implementations, in accordance with an embodiment, of the UE 22 and network node 16 discussed in the preceding paragraphs will now be described with reference to FIG.2. The communication system 10 includes a network node 16 provided in a communication system 10 and including hardware 28 enabling it to communicate with the UE 22. The hardware 28 may include a radio interface 30 for setting up and maintaining at least a wireless connection 33 with a UE 22 located in a coverage area 18 served by the network node 16. The radio interface 30 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and / or one or more RF transceivers. The radio interface 30 includes an array of antennas 35 to radiate and receive signal(s) carrying electromagnetic waves. In the embodiment shown, the hardware 28 of the network node 16 further includes processing circuitry 36. The processing circuitry 36 may include a processor 38 and a memory 40. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 36 may comprise integrated circuitry for processing and / or control, e.g., one or more processors and / or processor cores and / or FPGAs (Field Programmable Gate Array) and / or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 38 may be configured to access (e.g., write to and / or read from) the memory 40, which may comprise any kind of volatile and / or nonvolatile memory, e.g., cache and / or buffer memory and / or RAM (Random Access Memory) and / or ROM (Read-Only Memory) and / or optical memory and / or EPROM (Erasable Programmable Read-Only Memory). Thus, the network node 16 further has software 42 stored internally in, for example, memory 40, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the network node 16 via an external connection. The software 42 may be executable by the processing circuitry 36. The processing circuitry 36 may be configured to control any of the methods and / or processes described herein and / or to cause such methods, and / or processes to be performed, e.g., by network node 16. Processor 38 corresponds to one or more processors 38 for performing network node 16 functions described herein. The memory 40 is configured to store data, programmatic software code and / or other information described herein. In some embodiments, the software 42 may include instructions that, when executed by the processor 38 and / or processing circuitry 36, causes the processor 38 and / or processing circuitry 36 to perform the processes described herein with respect to network node 16. For example, processing circuitry 36 of the network node 16 may include a scheduler 32 which is configured to include a PHR unit 34. The PHR unit 34 may be configured to configure the UE to cease transmission of power headroom reports, PHRs, for the secondary cell when a difference between the power headroom of the primary cell and the power headroom of the secondary cell is less than a first threshold. The PHR unit 34 may also be configured to estimate power headroom for the secondary cell based at least in part on power headroom of the primary cell. The communication system 10 further includes the UE 22 already referred to. The UE 22 may have hardware 44 that may include a radio interface 46 configured to set up and maintain a wireless connection 33 with a network node 16 serving a coverage area 18 in which the UE 22 is currently located. The radio interface 46 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and / or one or more RF transceivers. The radio interface 46 includes an array of antennas 48 to radiate and receive signal(s) carrying electromagnetic waves. The hardware 44 of the UE 22 further includes processing circuitry 50. The processing circuitry 50 may include a processor 52 and memory 54. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 50 may comprise integrated circuitry for processing and / or control, e.g., one or more processors and / or processor cores and / or FPGAs (Field Programmable Gate Array) and / or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 52 may be configured to access (e.g., write to and / or read from) memory 54, which may comprise any kind of volatile and / or nonvolatile memory, e.g., cache and / or buffer memory and / or RAM (Random Access Memory) and / or ROM (Read-Only Memory) and / or optical memory and / or EPROM (Erasable Programmable Read-Only Memory). Thus, the UE 22 may further comprise software 56, which is stored in, for example, memory 54 at the UE 22, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the UE 22. The software 56 may be executable by the processing circuitry 50. The software 56 may include a client application 58. The client application 58 may be operable to provide a service to a human or non-human user via the UE 22. The processing circuitry 50 may be configured to control any of the methods and / or processes described herein and / or to cause such methods, and / or processes to be performed, e.g., by UE 22. The processor 52 corresponds to one or more processors 52 for performing UE 22 functions described herein. The UE 22 includes memory 54 that is configured to store data, programmatic software code and / or other information described herein. In some embodiments, the software 56 and / or the client application 58 may include instructions that, when executed by the processor 52 and / or processing circuitry 50, causes the processor 52 and / or processing circuitry 50 to perform the processes described herein with respect to UE 22. In some embodiments, the inner workings of the network node 16 and UE 22 may be as shown in FIG.2 and independently, the surrounding network topology may be that of FIG.1. The wireless connection 33 between the UE 22 and the network node 16 is in accordance with the teachings of the embodiments described throughout this disclosure. More precisely, the teachings of some of these embodiments may improve the data rate, latency, and / or power consumption and thereby provide benefits such as reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime, etc. In some embodiments, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. Although FIGS.1 and 2 show various “units” such as scheduler 32 and PHR unit 34 as being within a respective processor, it is contemplated that these units may be implemented such that a portion of the unit is stored in a corresponding memory within the processing circuitry. In other words, the units may be implemented in hardware or in a combination of hardware and software within the processing circuitry. FIG.3 is a flowchart of an example process in a network node 16 for estimating power headroom report in a secondary cell. One or more blocks described herein may be performed by one or more elements of network node 16 such as by one or more of processing circuitry 36 (including the PHR unit 34), processor 38, and / or radio interface 30. Network node 16 such as via processing circuitry 36 and / or processor 38 and / or radio interface 30 is configured to monitor a power headroom for a primary cell and for a secondary cell (Block S10). The method also includes configuring the UE to cease transmission of power headroom reports, PHRs, for the secondary cell when a difference between the power headroom of the primary cell and the power headroom of the secondary cell is less than a first threshold (Block S12). The method further includes estimating power headroom for the secondary cell based at least in part on power headroom of the primary cell (Block S14). According to this aspect, in some embodiments, the method includes monitoring an uplink signal to interference plus noise ratio, SINR. In some embodiments, the process includes configuring the UE 22 to cease transmission of PHRs for the secondary cell based at least in part on the SINR. In some embodiments, the process includes monitoring a primary cell bandwidth and a secondary cell bandwidth. In some embodiments, the process includes configuring the UE 22 to cease transmission of PHRs for the secondary cell based at least in part on the primary and secondary cell bandwidths. In some embodiments, the method includes monitoring a physical resource block, PRB, utilization of the primary cell and of the secondary cell. In some embodiments, the method includes configuring the UE 22 to cease transmission of PHRs for the secondary cell based at least in part on the monitored PRB utilizations. In some embodiments, the method includes configuring the UE 22 to resume transmission of PHRs for the secondary cell upon occurrence of an event. In some embodiments, the event is expiry of a timer. In some embodiments, the event is a change in power headroom of the primary cell exceeding a second threshold. In some embodiments, the event is a difference between power headroom of the primary cell and an estimated power headroom of the secondary cell exceeds a third threshold. In some embodiments, the event is a change in physical resource block utilization exceeding a fourth threshold. In some embodiments, the UE 22 is configured to cease or resume PHR transmissions for the secondary cell by radio resource control, RRC, signaling. In some embodiments, the method includes, when a difference between the estimated power headroom of the secondary cell and a periodically reported secondary cell power headroom reported by the UE 22 exceeds a threshold, configuring the UE 22 to commence transmission of secondary cell PHRs. Having described the general process flow of arrangements of the disclosure and having provided examples of hardware and software arrangements for implementing the processes and functions of the disclosure, the sections below provide details and examples of arrangements for estimating power headroom report in a secondary cell. FIG.4 shows a known network node in communication with a UE 22. In known configurations such as shown in FIG.4, the network node enables the UE 22 for multiple PHR in a configuration signaled via RRC signaling. The UE 22 then provides PHR for both the PCell and the SCell. FIG.5 shows a network node 16 configured according to principles disclosed herein to configure the UE 22 to make PHR for the PCell only when a difference between the power headroom of the primary cell and the power headroom of the secondary cell is less than a first threshold. Suppose a high band sector with a 400 MHz bandwidth is divided into four contiguous cells of 100 MHz each. Due to the contiguous spectrum, the use of the same radio unit for all four cells, and using analog beamforming, the channel conditions of these cells may be relatively similar. However, known approaches involve reporting of power headroom for the primary and secondary cells. To address this issue, a PHR unit 34 of the scheduler 32 in the network node 16 is configured to monitor factors such as delta Power headroom between PCell and Scell(s) over time, the difference in PRB utilization between primary cell (PCell) and secondary cell (Scell(s)), the UL SINR and the cell bandwidth of both primary and secondary cells. With this information, the PHR unit 34 may decide to stop reporting power headroom on the secondary cell and estimate the power headroom for the secondary cell based on a response received at the primary cell. To improve resource utilization, an example process implemented by the PHR unit 34 is shown in FIG.6 and involves the following steps: 1. Configuring multi PHR on UE (Block S122); 2. Receiving PHR for PCell and Scell(s) (Block S124); 3. Monitoring parameters such as delta Power headroom between PCell and Scell(s) over time, delta PRB utilization between PCell and SCell(s), UL SINR and cell bandwidth (Block S128); 4. Determining the difference between estimated and the actual PHR and if SCell estimation is possible (Block S130): 5. If the difference is below a threshold (for example 10%) (Block S30), then: a.) configuring single PHR on the UE (Block S132); and b.) estimating PHR for Scell (Block S134); 6. If the difference is above the allowed threshold (for example 10%), the process may return to Block S122, where a legacy approach may be used until there is enough confidence to estimate the PHR for the secondary cell. As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, computer program product and / or computer storage media storing an executable computer program. Accordingly, the concepts described herein may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a “circuit” or “module.” Any process, step, action and / or functionality described herein may be performed by, and / or associated to, a corresponding module, which may be implemented in software and / or firmware and / or hardware. Furthermore, the disclosure may take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in the medium that may be executed by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD-ROMs, electronic storage devices, optical storage devices, or magnetic storage devices. Some embodiments are described herein with reference to flowchart illustrations and / or block diagrams of methods, systems and computer program products. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer (to thereby create a special purpose computer), special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks. These computer program instructions may also be stored in a computer readable memory or storage medium that may direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instruction means which implement the function / act specified in the flowchart and / or block diagram block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks. It is to be understood that the functions / acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality / acts involved. Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows. Computer program code for carrying out operations of the concepts described herein may be written in an object oriented programming language such as Python, Java® or C++. However, the computer program code for carrying out operations of the disclosure may also be written in conventional procedural programming languages, such as the "C" programming language. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user's computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments may be combined in any way and / or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination. It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope of the following claims.

Claims

What is claimed is:

1. A method in a network node (16) configured to communicate with a user equipment, UE (22), the method comprising: monitoring (S10) a power headroom for a primary cell and for a secondary cell; configuring (S12) the UE (22) to cease transmission of power headroom reports, PHRs, for the secondary cell when a difference between the power headroom of the primary cell and the power headroom of the secondary cell is less than a first threshold; and estimating (S14) power headroom for the secondary cell based at least in part on power headroom of the primary cell.

2. The method of Claim 1, further comprising: monitoring an uplink signal to interference plus noise ratio, SINR; and configuring the UE (22) to cease transmission of PHRs for the secondary cell based at least in part on the SINR.

3. The method of any of Claims 1 and 2, further comprising: monitoring a primary cell bandwidth and a secondary cell bandwidth; and configuring the UE (22) to cease transmission of PHRs for the secondary cell based at least in part on the primary and secondary cell bandwidths.

4. The method of any of Claims 1-3, further comprising: monitoring a physical resource block, PRB, utilization of the primary cell and of the secondary cell; and configuring the UE (22) to cease transmission of PHRs for the secondary cell based at least in part on the monitored PRB utilizations.

5. The method of any of Claims 1-4, further comprising configuring the UE (22) to resume transmission of PHRs for the secondary cell upon occurrence of an event.

6. The method of Claim 5, wherein the event is expiry of a timer.

7. The method of Claim 5, wherein the event is a change in power headroom of the primary cell exceeding a second threshold.

8. The method of Claim 5, wherein the event is a difference between power headroom of the primary cell and an estimated power headroom of the secondary cell exceeds a third threshold.

9. The method of Claim 5, wherein the event is a change in physical resource block utilization exceeding a fourth threshold.

10. The method of any of Claims 1-9, wherein the UE (22) is configured to cease or resume PHR transmissions for the secondary cell by radio resource control, RRC, signaling.

11. The method of any of Claims 1-10, further comprising, when a difference between the estimated power headroom of the secondary cell and a periodically reported secondary cell power headroom reported by the UE (22) exceeds a threshold, configuring the UE (22) to commence transmission of secondary cell PHRs.

12. A network node (16) configured to communicate with a user equipment, UE (22), the network node (16) configured to: monitor a power headroom for a primary cell and for a secondary cell; configure the UE (22) to cease transmission of power headroom reports, PHRs, for the secondary cell when a difference between the power headroom of the primary cell and the power headroom of the secondary cell is less than a first threshold; and estimate power headroom for the secondary cell based at least in part on power headroom of the primary cell.

13. The network node (16) of Claim 12, wherein the network node (16) is configured to: monitor an uplink signal to interference plus noise ratio, SINR; and configure the UE (22) to cease transmission of PHRs for the secondary cell based at least in part on the SINR.

14. The network node (16) of any of Claims 12 and 13, wherein the network node (16) is configured to:monitor a primary cell bandwidth and a secondary cell bandwidth; and configure the UE (22) to cease transmission of PHRs for the secondary cell based at least in part on the primary and secondary cell bandwidths.

15. The network node (16) of any of Claims 12-14, wherein the network node (16) is configured to: monitor a physical resource block, PRB, utilization of the primary cell and of the secondary cell; and configure the UE (22) to cease transmission of PHRs for the secondary cell based at least in part on the monitored PRB utilizations.

16. The network node (16) of any of Claims 12-15, wherein the network node (16) is configured to configure the UE (22) to resume transmission of PHRs for the secondary cell upon occurrence of an event.

17. The network node (16) of Claim 16, wherein the event is expiry of a timer.

18. The network node (16) of Claim 16, wherein the event is a change in power headroom of the primary cell exceeding a second threshold 19. The network node (16) of Claim 16, wherein the event is a difference between power headroom of the primary cell and an estimated power headroom of the secondary cell exceeds a third threshold.

20. The network node (16) of Claim 16, wherein the event is a change in physical resource block utilization exceeding a fourth threshold.

21. The network node (16) of any of Claims 12-20, wherein the UE (22) is configured to cease or resume PHR transmissions for the secondary cell by radio resource control, RRC, signaling.

22. The network node (16) of any of Claims 12-21, wherein, when a difference between the estimated power headroom of the secondary cell and a periodically reported secondary cell power headroom reported by the UE (22) exceeds a threshold, the networknode (16) is configured to configure the UE (22) to commence transmission of secondary cell PHRs.

Images